1. Field
This application relates to medical instruments used to reach the esophagus through the mouth for diagnostic or therapeutic purposes.
2. Prior Art
Echocardiography is considered as one of the most significant advancements in medical science of the past century.
Nonetheless a consecrated tool in the specialty, it found substantial limitations inherent to the physics of the instrumentation. The resolution of the images, an indispensable feature in the accuracy of any imaging modality, is drastically diminished by the distance of the interrogation point and the ultrasound transducer. The interposition of air also renders the tool useless since ultrasound waves cannot be transmitted through this media. Therefore, obesity, COPD and senile emphysema, are conditions that present an insurmountable challenge to the conventional technology. Patients in the intensive care unit undergoing mechanical ventilation also present outstanding difficulties for the transthoracic echocardiographic evaluation. Trans esophageal echocardiography is a technology that came to overcome the above mentioned limitations and became irreplaceable, in circumstances in which ultrasound images of the heart were required and a conventional transthoracic approach was suboptimal. In addition, new indications came to solidify the need for this technology as are the investigation of valvular vegetations, atrial clots, and the presence of patent foramen ovale in addition to intraoperative monitoring of valvular surgery, precardioversion evaluation, among others. One of the most commonly encountered problems with this technology is the passage of the probe in to the esophagus. A substantial limitation is the physical constraint that requires a bulky shape and size of the distal probe that harbors the ultrasound crystals and mechanical components.
The passage of such an element through the orophagyngeal area presents self-evident difficulties. The gag reflex is a life preserving characteristic that makes any attempts to introduce any bulky material into the esophagus a very difficult endeavor. Not unexpectedly, the process of passing of the probe through the throat in to the esophagus is the origin of most the complications of the procedure namely, trauma to the larynx or pharynx, bleeding, pain, abscess formation not to mention the discomfort of withstanding such an unnatural procedure. In an attempt to circumvent these limitations, sedation is included routinely. There is no a particular protocol or method to warrant an easy passage of the TEE probe into the esophagus. The probe is supposed to advance straight down into the mid portion of the posterior pharyngeal wall and then by further pressing on the posterior wall the tip should advance into the esophagus since the posterior pharyngeal wall continues seamlessly with the posterior esophageal wall. This process is tainted, by the fact that the procedure is done blindly since the probe has to pass beyond the line of sight behind the base of the tongue, before entering into the esophagus. In addition, esophageal opening 24, FIG. 4 is a virtual space that only opens up during the deglutition process. Therefore, near 100% of the cross sectional area at the level of esophageal opening 24, FIG. 4 is comprised by glottis 26, epiglottis 27 and pyriform sinuses 29. In the usual protocol the transesophageal probe is pushed blindly against a closed esophagus assuming that the tip is positioned medially so it will fall against the esophageal opening. Many times, the patient is called to help by trying to swallow the probe, in very unfriendly circumstances. In addition, a particular disadvantage of transesophageal probes in comparison with gastric endoscopes is that the distal angulation does not follow an even curvature but it has an inflection point caused by the unyielding nature of the rigid case in the distal 7 cm of the probe. This unavoidable physical constrain is the reason of the much more difficult negotiation of the TEE probe into the esophagus. Other techniques used by physicians like using the fingers to manipulate the distal end of the probe or the use of laryngoscopes to visualize the esophageal opening are also used, albeit at the cost of increased discomfort and potential complications for patients and operators.
Even more, the introduction of conscious sedation to decrease the anxiety of the procedure adds another component of risk and the more difficult the passage of the probe is, the more sedation is needed. Depending of the level of sedation, the patient loses the ability to defend itself against the aggression of the procedure and cases of tracheal intubation and aspiration have been well documented. Previous attempts have been made to create a device that would facilitate the esophageal intubation for transesophageal echocardiograms, however none of them were able to gain acceptance.
Douglas U.S. Pat. No. 4,195,624, filed Jun. 9, 1978, describes a device to facilitate the insertion of an endoscope into the esophagus made of a flexible elastomer and a solid tapered tubular end into which the tip of the probe is inserted. Embodiment only add a tapered end to the endoscope but does not facilitate the location of the esophageal opening and obliges to use a large volume tubular structure as the tool to find the opening which seriously limit the accuracy of the maneuvers when the tip is behind the tongue.
Griffith U.S. Pat. No. 5,390,661, filed Feb. 3, 1993, presents an introducer with a pilot member and a coaxially fitting sheath. The first embodiment is a device similar to a medical endoscope steerable fitting into a sheath that can be used as the pilot member. Albeit the steer ability is an attractive feature, the cost makes it a less desirable device.
Kawahara U.S. Pat. No. 3,913,565, filed Apr. 25, 1974, describes a guide tube to insert instruments into body cavities. Albeit this device was also for esophageal introduction, is merely a flexible tube to guide an endoscope but does not facilitate the localization of the esophageal opening.
Park U.S. Pat. No. 5,279,610, filed Nov. 6, 1992, describes a three component structure with a semi rigid sheath, a coaxial introducer guide and a dilator tip. Again, it does not provide a straightforward method that allows the introducer guide to find the esophageal opening.
Pastron US patent application 2013/0006057, filed Dec. 29, 2011, describes a device to keep the mouth open during procedures done through the mouth. It serves as a tongue depressor that goes as far as the posterior aspect of the tongue. However, even though it provides a light source and passage ways for catheters, this does not facilitate the introduction of medical probes into the esophagus. Besides, the device aims to decrease the gag reflex but it places the distal portion thereof on the posterior aspect of the tongue where the gag reflex is mostly located.
Karakurum US patent 2008/0103508 A1 filed Nov. 1, 2006, describes an esophageal overtube with a basket at the distal end for retrieval of impacted food bolus. It does not describe an easy way into the esophagus but with an endoscope.
Balbierz US patent application 2008/008726, filed Jul. 17, 2008, describes an esophageal overtube that is preferably inserted with the guidance of an endoscope or through a guide wire that itself has to be inserted through an endoscope. Albeit the tube is designed to facilitate the repeated insertion of endoscopes during the same procedure, It still requires an endoscope for its initial insertion.
Cole US patent application 2009/0030284A1, filed Jul. 17 2008, describes a large introducer tube as part of an assembly for intragastric procedures. Preferably it has to be inserted with the use of an endoscope, alternatives embodiments include a wire that has to be inserted with an endoscope and then the tube has to have a tapered adaptor to follow the wire. A bougie with a snug fit at the distal end and a umbrella type device at the distal end are ways to introduce the tube without the need of an endoscope, but the difficulties finding the esophageal opening without direct visualization remains unsolved as with prior devices.